The conventional system by which mail is currently identified and processed (e.g., sorted) is highly automated, but still requires both human and mechanical operations. Human operations are initially required to load the mail from a mail delivery repository into a mechanical identification and processing system. Mechanical operations then attempt to identify the delivery address for each mail piece and, if successful, to then process each mail piece based on the delivery address. If there is a failure to identify the delivery address of a mail piece mechanically, human operators are required to identify the delivery address. Likewise, if there is a failure to process the mail piece based on the delivery address, human operators are again required to process the mail piece. As a result, conventional systems for identifying and processing mail must be reliable if the need for human operators and oversight is to be minimized.
A typical mail processing machine comprises a series of modules, components, and subassemblies which perform independent functions in the mail sorting process. For example, after the mail is collected, the sorting process typically begins with a Dual Pass Rough Cull System (DPRCS). As mail travels through the DPRCS, large items, such as packages and mail bundles, are removed from the mail stream. The remaining mail then enters an Advanced Facer-Canceler System (AFCS), the first machine for processing standard mail, where postage is cancelled. Pieces that pass through the DPRCS, but do not conform to physical dimensions for processing in the AFCS (i.e., over-sized items) are also diverted from the stream.
The mail remaining in the mail stream, or feed path, can then be fed past an optical character reader (OCR) or Bar Code Reader (BCR), which reads or scans the delivery address from the mail piece and causes a special code (e.g., a bar code), corresponding to the delivery address or other pertinent information, to be printed or “sprayed” on the mail piece. Once coded, the mail can be automatically sorted by a Delivery Bar Code System that reads the code and determines the destination postal station of the mail piece.
Typically, OCRs, BCRs, and other machines of the type described above are capable of operating at a rather high rate of speed, usually processing on the order of 100 to 400 pieces of mail per minute. At this rate, it is often crucial that the mail pieces enter the feed path of the mail processing machines one at a time and not overlapping one another.
If more than one mail piece is permitted to travel down the feed path at one time, several problems may arise. For example, an OCR or similar device may not be able to read the delivery address printed on a piece of mail if the address is eclipsed or otherwise obscured by an overlapping mail piece. Also, where a second mail piece is completely overlapping a first, the address on the second piece may be scanned and that information may be inadvertently sprayed on the back of the first mail piece, resulting in a missort. Additionally, overlapping mail pieces can lead to paper jams and excessive wear on the sorting components. This results in machine down-time and the need for costly and time consuming repairs.
Thus, “double inhibit” mechanisms are commonly employed within item handling machinery, such as mail processing machines, in an attempt to ensure that only single items are traveling down the handling path, past the various modules or components. Although the following discussion is generally directed to double inhibit mechanisms in mail processing machinery, the invention is not so limited, and may be employed in other types of item handling machinery.
The double inhibit mechanism may include friction elements placed opposite the feed belts of the mail processing machine. The coefficient of friction existing between the friction elements and a mail piece is typically less than that found between the feed belts and a mail piece, but greater than that found between two mail pieces. As a result, when two pieces of mail pass between the friction elements and the feed belts, the friction element may contact the second mail piece and the frictional forces therebetween, which are greater than those between the two mail pieces, will prevent it from passing by. But when only one piece passes between the feed belts and the double inhibit mechanism, the friction between the mail piece and the feed belt is great enough to overcome any frictional forces imparted by the device's friction elements and the mail piece is able to continue down the mail path.
Unfortunately, friction elements currently in use are not always reliable. Occasionally, as a mail piece traveling down the mail path attempts to move past the friction elements of a double inhibit mechanism, the mail piece's striking of the friction element can cause the friction element to “bounce” or lose contact with the mail as it travels down the mail path. When contact with the mail is disrupted, the chance for overlapping mail pieces to make their way past the double inhibit mechanism is greatly increased.
Accordingly, it is desirable to provide an improved double inhibit mechanism which addresses the shortcomings set forth above.